Vascular diseases such as cardiac infarction rank among the most frequent diseases resulting in death. They are caused by diseases of the blood vessels where plaque deposits have resulted in a narrowing or “blocking” of the blood vessels. One treatment possibility is to extend the constrictions of, for example, the coronary vessels with a so-called “balloon catheter”, to which end, a guide wire is passed through the vascular system into the area of the constriction that is to be treated. A guide catheter can then be moved over the guide wire to the ostium of the coronary artery, wherein, in the so-called “over-the-wire” method, a balloon catheter is introduced over the guide wire inside the guide catheter. The balloon at the distal end of the catheter is then inflated and the stenosis widened. Medical instruments are also inserted into the body of the patient in a similar way in the case of other diseases.
As a rule, treatments of this kind are carried out using X-ray control after the administration of a contrast medium. The medical instruments used, such as, for example, catheters or guide wires, are equipped with a position sensor system, which is in most cases magnetic or electromagnetic and which has in addition external components such as transmitters or receivers outside the body, in order thus to locate the instrument in the body of the patient and to track and monitor the treatment. The monitoring is used, for example, to prevent the instrument from causing damage to the vascular systems.
Positioning or locating systems of this kind currently involve computational effort that cannot be neglected, in order to determine the actual position, as for the human body, for example, as described in DE 42 15 901 A1, the model of an infinite monochromatic conductive half-space is assumed. Thus the search area that a data processing system runs through for the location in order to actually determine the position, is infinite, so that the reconstruction time until images are actually present can be very long depending on the available computer system. Therefore, considerable computing resources are required and also the treatment may be unnecessarily drawn out due to delays.